15 cultivars of covered oats grown in ’94 and 4 cultivars of naked oats grown in ’95 were investigated. The nutrients content and amino acid composition were determined. Biological value (BV) and true digestibility (TD) were evaluated in balance trials on rats. Naked oat had higher crude protein and fat content, and lower crude fibre and ash than covered oat. BV and TD of protein of naked oat were also higher. Significant (P < 0,01) relationship between BV and lysine level (r = 0,69) or BV and EAAI (r = 0,77) were found. TD negatively correlated with crude fibre content (r = – 0,69; P < 0,01). Oats cultivar: Akt (naked) and Boryna (covered) had the best nutritive value of protein.